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Several fish species have been successfully cultured in aquaponic systems. Overall growth parameters of these are given in Table 4. Important factors when deciding on the proper species also include availability of quality brood-stock or fingerlings, growth rate to market size, and feed cost and supply. Freshwater species are preferred, as most of the plant crops produced in aquaponics have very low tolerance of salinity. Also, hybrid striped bass (Morone chrysops x M. saxatilis), which can be raised in aquaculture recycle systems, are reported to do poorly in aquaponics due to intolerance of the high potassium levels supplemented to support plant growth (Rackocy et al. 2006), though they have been grown successfully (Diessner 2013).
Table 4: Summary of fish species suitable for aquaponics.
| Species | Temperature (C) | Total ammonia nitrogen (mg/L) | Nitrite (mg/L) | Dissolved oxygen (mg/L) | Crude protein in feed (%) | Growth rate | Year-round supply of fingerlings (US) | Market value ($US/lb live) | Consumer Acceptance | |
|---|---|---|---|---|---|---|---|---|---|---|
| Vital | Optimal | |||||||||
| Nile tilapia Oreochromis niloticus | 4-34 | 25-30 | < 2 | < 1 | > 4 | 28-32 | 600g in 6-8 months | Yes | $3.00 | Good |
| Common carp Cyprinus carpio | 14-36 | 27-30 | < 1 | < 1 | > 4 | 30-38 | 600g in 9-11 months | Yes | NA | Poor |
| Channel catfish Ictalurus punctatus | 5-34 | 24-30 | < 1 | < 1 | < 3 | 25-36 | 400g in 9-10 months | Yes | $2.00 | Good |
| Largemouth bass Micropterus salmoides | 5-34 | 24-30 | < 1 | < 2 | > 4 | 45-48 | 600g in 14-16 months | Seasonal | $4.00-5.00 | Moderate |
| Rainbow trout Oncorhynchus mykiss | 10-18 | 14-16 | < 0.5 | < 0.3 | > 6 | 42 | 1,000g in 14-16 months | Seasonal | $3.00 | Good |
| Barramundi Lates calcarifer | 18-34 | 26-29 | < 1 | < 1 | > 4 | 38-45 | 400g in 9-10 months | No | $8.00-9.00 | Good |
Tilapia: Tilapia (usually Oreochromis niloticus or the Nile tilapia) are the most cultured fish in aquaponic systems. They are tolerant of both crowding and relatively poor water quality conditions. They do best at water temperatures of 25-30°C. At temperatures < 24°C, their growth slows substantially, and they become susceptible to disease. They breed readily and abundantly. In fact, if using mixed sex fish, unintended spawning in the system can be a problem particularly in DWC beds where tilapia will consume all available plant roots. Monosex fish (all male) are available and preferred. Tilapia are widely accepted in the marketplace. If available, ethnic markets, which accept live or whole fish, should be considered. The tilapia is most efficient when grown to 3/4-1 lb. in final weight. For processed products, such as fillets, tilapia must be raised to large sizes since they have low fillet yields (33% of body weight) compared to other species. Producers who choose to culture tilapia can be in competition with imported frozen product or with large domestic recycle systems, which drives down market price.